588 H. p. KJERSCHOW AGBRSBORG 



tentacle (lamellar papilla of Gould), ^fb, nerve-fibres of a highly gan- 

 glionic knob ; Nfi, the same fibres in the lamellated part ; Nfp, nerve- 

 iibres which communicate with the peripheral ganglion below (*S') ; 

 Nc, small nerve-cells surrounding central fibres ; Ncs, ganglionic knob, 

 consisting of nerve-cells only ; Nmf, neuro-muscular fibres which inter- 

 communicate between the sense organ and the base of the tentacle ; 

 Out, the outer wall of the tentacle which serves as a sheath to the organ ; 

 8, lamellae, x 75. 



Fig. 16. — Nerve-ceUs from ' ^ ' in figs. 8 and 15. Nc, larger nerve-cells ; 

 Ncs, smaller nerve-cells. Notice the large granular nucleus, x 1,013-4. 



Fig. 17. — Front view of Melibe leonina. Fh, rim of hood; Fr, 

 front ; Ft, foot ; Ire, inner row of cirrhi ; Irc^, mid-ventral rudimentary 

 cirrhi ; L, lip ; M, mouth ; Mf, muscle-fibres ; Mdp, mid-dorsal depres- 

 sion ; Ore, outer row of cirrhi ; R, base of tentacle. X 1 J. 



Figs. 18-24.— Papillae. Figs. 18, 19, first pair; 20, one of the second 

 pair ; 21, one of the third pair ; 22, one of the fourth pair ; 23, one of 

 the fifth pair ; 24, the sixth pair. Hep, caecal terminal branches of the 

 liver. The parallel lines represent muscle-fibres, x 1 . 



Fig. 25. — Longitudinal section of an anterior papilla. Cshh, cross- 

 section of a hepatic branch ; Mf, muscle-fibres ; Og, odoriferous gland ; 

 Osp, vascular space or sinus ; Tbr, tubercles, x 2. 



Fig. 26. — Cross-section through the anterior region of the foot. Cil, 

 cilia : Lv, liver ; Mc, muscle-bundle ; Og, odoriferous gland ; Thr, 

 tubercles, x 8. 



Fig. 27. — Cross-section through the posterior region of the foot. Be, 

 connective tissue ; 01, pedal ganglion. The other labelling as the preceding. 

 x8. 



Fig. 28. Section of a single tubercle from the anterior end of the foot. 

 Cex:,, ciliated columnar ectoderm ; Cil, cilia ; Omug, granules of mucous 

 glands ; Grc, granular border ; Mf, muscle-fibres ; Nf, nerve-fibres ; 

 Ng, nerve-cells ; Nu, nucleus. 



Fig. 29. — Section through the pedal ganglion of the foot (vide fig. 27). 

 Cec, ciliated columnar ectoderm ; Cil, cilia ; Gl, ganglionic cells ; Mf, 

 muscle-fibres ; Mug, mucous glands with crypts passing through ectoderm ; 

 Nf, nerve-fibres ; Ng, nerve-cells ; Nt, neural fibrillae ending on to ciliated 

 ectoderm ; Pdng, pedal ganglion. 



Fig. 30. — Section through the body- wall. Bv, body- wall ; Cr, crypt ; 

 Ct, connective tissue ; Ee, ectoderm ; 8m, saccular mucous gland ; ^Ib, 

 muscle-bundle ; yif, muscle-fibres ; Glo, odoriferous glands ; Vm, uni- 

 cellular gland. 



Fig. 31. — Section from part of the wall of a large papilla (see fig. 25). 

 C'c, connective-tissue cells ; Ch, cross-section of hepatic branches ; Ct, 

 connective-tissue fibres ; Glo, odoriferous gland ; Pec, ectoderm of 

 fimbriated surface. 



